Provided here are process and systems relating generally to the separation of 1,4-butanediol or a target compound from fermentation broths.
1,4-Butanediol (1,4-BDO) is an industrial polymer intermediate useful for synthesizing polyester resins, gamma-butyrolactone, tetrahydrofuran, and other compounds. Industrial syntheses of 1,4-butanediol using nonrenewable petrochemical feedstocks are known, as are process for purifying 1,4-butanediol from crude 1,4-butanediol obtained from petrochemical based syntheses (see, e.g., Okuyama, U.S. Pat. No. 5,981,810). Fermentation production of 1,4-butanediol is an alternative to traditional production using nonrenewable petrochemical feedstocks. For instance, fermentation production utilizes renewable feedstocks such as biomass or other bio-based feedstocks, and the process can be more environmentally sound than petrochemical based production. Separating 1,4-butanediol from other components within fermentation broths, however, requires different procedures than those applicable for purifying 1,4-butanediol from petrochemical based syntheses due, for example, to the different types of components present in fermentation broths.
Adkesson et al., U.S. Pat. Pub. No. 2005/0069997 describes a process for separating 1,3-propanediol from a fermentation broth. The process in Adkesson et al. includes filtration, ion exchange and distillation, wherein distillation consists of four columns and can include a hydrogenation step between columns 2 and 3. Clark et al., WO 2010/141780 describes separating 1,4-butanediol from a fermentation broth. The process includes separating a liquid fraction from a solid fraction, removing salts from the liquid fraction, and separating the product in a series of distillations, to remove water and other light components in one distillation column and to remove heavy materials with boiling points lower than the product in another distillation column.
Challenges remaining for obtaining 1,4-butanediol or target compound from fermentation broths can include, for instance, increasing yield or purity of the 1,4-butanediol or target compound obtained from fermentation broths, reducing process steps or system components and/or reducing levels of certain particular contaminants, among other things. For example, obtaining 1,4-butanediol from fermentation broths can include undesirable organic acids and other substances, either in a fermentation broth or that are formed during steps of a procedure of purifying 1,4-butanediol, which can react with 1,4-butanediol effectively lowering yields.